Field of the Invention
The present invention relates to an ozone-water feeding facility used for applications in which human bodies, instruments and articles are cleaned with ozone-water for sterilization at working sites associated with medical care, public health, the chemical industry, the food processing industry and the like. In particular, it relates to a facility for feeding ozone-water from an ozone-water producing apparatus to a remote service location by way of a pipeline.
An ozone-water producing apparatus for dissolving ozone gas in water filled in a tank while agitating and circulating the water in the tank is known, for example, from Japanese Patent Laid-open No. Hei 2-7967. The apparatus has a faucet from which ozone-water is discharged to be used, for example, for cleaning hands and fingers of a person.
As a method of feeding ozone-water from an ozone-water producing apparatus to a remote service location, a side stream method is known. For example, in U.S. Pat. No. 5,040,487, ozone-water is fed from an ozone-water producing apparatus to a lake by way of a long transportation pipeline in order to sterilize water in the lake.
In the case where ozone-water is fed from an ozone-water producing apparatus to a remote service location by way of a long pipeline laid therebetween and is intermittently discharged at the service location, a serious problem occurs in that it becomes difficult to keep a specific concentration of the ozone-water. This results from the fact that the half-life of ozone dissolved in water is much shorter than that of any other sterilizer.
The decay of the concentration of ozone-water will be more fully described below. A concentration Cx of ozone-water, which has decayed until the ozone-water having been fed from an ozone-water producing apparatus reaches a remote ozone-water service location by way of a pipeline, is expressed by EQU C.sub.x ={(1/2).sup.Kx }Co, with Kx={Lx/(Vx/Sx)}/T
where T is a half-life of ozone in the ozone-water, Co is a concentration of the ozone-water at the outlet of the ozone-water producing apparatus, Cx is a concentration of the ozone-water at the service location, Lx is a length along the pipeline in a region from the ozone-water producing apparatus to the service location, Sx is an average effective cross-sectional area of the pipeline, and Vx is an average flow rate (in volume per unit time) of the ozone-water passing through the pipeline in the region from the ozone-water producing apparatus to the service location. With respect to the half-life T of ozone, data described in "Ozone Yearbook in 1993-1994" published by Kabushiki Kaisha Realize show that T is as short as somewhere from ten to twenty minutes in a usual environment (neutral underwater). Now, it is assumed that the facility is used in a favorable environment with T set at 20 minutes, and the other factors are selected such that Lx is 10 m, Vx is 500 cc/min, and Sx is about 0.5 cm.sup.2 (effective inside diameter of the pipeline: 8 mm). Under this assumption, in the case of continuous discharge of the ozone-water, Kx becomes about 1/20. Therefore, the value Cx/Co becomes about 0.966, which means that the decay of the concentration of the ozone-water is negligible in accordance with a usual allowable level. In many cases, however, the ozone-water is intermittently discharged, for example, 100 cc one hour apart. In this case, it takes five hours until the ozone-water flows from the inlet of the pipeline to the outlet of the pipeline. Therefore, the value Cx/Co becomes 1/32768, which means that ozone in the ozone-water is almost lost.
If the ozone-water has entirely lost its sterilizing ability as a result of the reduction in concentration of the ozone-water by the intermittent discharge of the ozone-water, a user who has not been advised of the decay of the concentration of the ozone-water is not aware that the sterilizing ability of the ozone-water is lost, and he may have an illusion that hands and/or fingers of the user are sufficiently sterilized with the ozone-water. This is very hazardous from the viewpoint of health conservation.
On the other hand, a user having recognized such a problem will inconveniently throw away the initial part of the ozone-water before every use of the ozone-water. Such action creates wasted time and gives rise to wasted ozone-water. For example, in the above configuration of the facility, to intermittently use the ozone-water at a specific concentration, about 500 cc of the initial part of the ozone-water remaining in the flow passage having a length of 10 m is thrown away, and the subsequent part of the ozone-water is used during every usage of the ozone-water. This not only takes a lot of labor for handling the facility but also causes a large waste of the ozone-water, that is, 500 cc of the ozone-water are wasted for every 100 cc of the ozone-water used.
The above throw-away of the initial part of the ozone-water until the discharge of the subsequent part of the ozone-water having a specific concentration presents another problem. The thrown-away initial part of the ozone-water, particularly, the latter half of the thrown-away initial part has a concentration lower than the desired concentration, but it contains ozone in an amount not negligible in terms of influence to a human body or peripheral environment. Therefore, the facility must be provided with equipment for rendering the thrown-away ozone-water harmless. This requires an excess space for provision of the equipment and an excess cost for production of the equipment.
In the case described in the above document, U.S. Pat. No. 5,040,487, it is conjectured that ozone-water may be discharged in the lake in the form of non-controlled effluent. Consequently, it may be considered that the rate of continuous discharge of the ozone-water becomes significantly large, and therefore, a large problem does not occur. As is apparent from the above description, if the ozone-water is intermittently discharged in the case described in U.S. Pat. No. 5,040,487, there may occur the above-described problem associated with the reduction in concentration of the ozone-water.